Can We Emulate Early Seral Forest Through Silviculture

Can we emulate early seral forest through silviculture?

Klaus J. PuettmannEdmund Hayes Professor in

Siviculture Alternatives

Adrian AresResearch Associate

Oregon State University

Background– Structure – Composition– Legacies

Management of vegetation– after stand replacing disturbances– after partial disturbances

o - Thinning o - Gaps

Outline

Early seral forestconditions after a disturbance

that removes overstory

Background

Structure: “Open growing space”; allowing for establishment of vegetation and associated insects, animals, etc.– Shift towards “tall” canopy layers

Composition: dominance of early successional species– Shifts towards late seral species

(within and among canopy layers) Legacies from pre-disturbance

vegetation

Background

Legacies Important for ecosystems

processes and function

Influence development of early and late seral conditions– Sprouting– Seed source– Cover that prevents

establishment of early seral species

Background

Suislaw NF Willamette NF

From Yang et al. 2005

Structural development of plantations Conifer cover

20 years6 years 13 years

Management – Stand replacing disturbances

ODF land OR Coast Range

Dave Powell, USDA Forest Service, Bugwood.org


“Arrested” stand development Ceanothus after wildfire, Umatilla NF

P. Anderson, USFS

L. Kayes L. Kayes

2nd growing season

3rd growing season

Management – Stand replacing disturbancesImpacts of legacies – Sprouts

Timbered Rock, BLM

P. Anderson, USFS


Shrub removal No treatment

Hardwood control initially maintains “open” structure

T. Harrington USFS


Intensive hardwood control accelerates dominance of conifers

Unmanaged

125 snags/ha (range 21-229 )


0

10

20

30

40

50

60

# D

omin

ant s

eedl

ings

est

ablis

hed/

year

0

10

20

30

40

50

60

Years after fire

2 4 6 8 10 12 14 16 18 200

10

20

30

40

50

60

2005

2005

C

2005

B

A

High elevation

Low to moderate elevation

Natural regeneration (no salvage logging or planting) suggest longer early seral phase


# d

om

ina

nt

se

ed

ling

se

sta

blis

he

d

Conifer size distribution

DBH (cm)

0 2 4 6 8 10 12 14 16 18 20 22 24

Con

ifers

/ ha

0

50

100

150

200

1500

2000

2500 Unmanaged Managed

M. J. Lopez 2008

•Management (salvage, fuel treatment, planting, release) speeds up conifer dominance* Spatial evenness (!!)


> 15 feet = gap

How many gaps are in ODF plantations?


Low density

Gap Road

Measurement line

0.0

2.0

4.0

6.0

8.0

10.0

12.0

1984 1986 1988 1990 1992 1994 1996

YEAR planted

% a

rea

in g

ap

Puettmann and Berger 2005


Gaps contain early seral vegetation, but disappear as stands develop

Spatial scale and variability

Timber production

Structural Diversity


No management Management – keep gaps open

Gap - scale

Management – stand replacing disturbances

Ongoing studies:

6% of plantation in gaps

Does wildlife notice the difference?

Gap and stand scale


Ongoing studies:

YSTDS - Christy Flats

Management – Partial disturbancesThinning and gaps = managing for early seral legacies in mature forests

Un

der

sto

ry S

pec

ies

Ric

hn

ess

(#

/ plo

t)

0

5

10

15

20

25

30

Late Seral Forest Omni-presentOpen / Early Seral

Control High Moderate Variable density

Modified from Berryman, unpubl.

Management – Partial disturbances

Structural development:

Herbs take advantage of disturbance

Tall shrubs recover slow

Study Results

0

10

20

30

40

0

10

20

30

40

ControlHeavy thinningLight thinningLight thinning w/gaps

Co

ve

r (%

)

0

10

20

30

40

0

10

20

30

40

Herbs

Low shrubs

Tall shrubs

Bryophites

aabb

a

aaa

b

a

bbb

a

bb

b

a

bb

b

a

bbb

1 3 5 10 Year

a

bb

b

aabab

b

From Ares et al. 2009


Harvesting layout to protect shrubs (legacies)


0

5

10

15

20

25Ric

hnes

s (n

o. s

peci

es)

0

5

10

15

20

25

Cov

er (%

)

All herbs Forest herbs Early seral herbs Later seral herbs P = 0.04 P < 0.001

P < 0.001

P = 0.02

P < 0.001

(a) (b) (c) (d)

(e) (f) (g) (h)

A

ABB AB

AB

B B

A

B B B

AC BC BCB

A

B B B

C LC MC HC C LC MC HC C LC MC HC C LC MC HC

From Ares et al. 2009


Early seral herbs are responsive: structure and composition

C = ControlLC = Low complexity thinningMC = Moderate complexity thinningHC = High complexity thinning

Co

ver

(%)

0

15

30

45

60

A

A

AA

C LC MC HC C LC MC HC C LC MC HC

Ric

hn

ess

(no

. sp

ecie

s/p

lot)

0

15

30

45

60

A AB BC C

AB B

AB

All shrubs Forest shrubs

A AB BC C

A B B B

A B B

Early seral shrubs

B

P < 0.001 P < 0.002 P < 0.001

P = 0.03 P < 0.001

(a) (b) (c)

(d) (e) (f)


Shrub layer slow to recover and dominated by “legacies”

C = ControlLC = Low complexity thinningMC = Moderate complexity thinningHC = High complexity thinning

Co

ver

(%)

0

10

20

30

40

b

a

a

a a

ab

CON HD MD VD300 VD200 VD100

Early seral vegetation 11-years after thinning


“Long-term” impact

C = ControlHD = High densityMD = Moderate densityVD = Variable density

Lindh and Muir 2004


Gap influence Encourages early seral

vegetation Limited to “gap” Early seral species

– Physical disturbance

– Competition for light (large gaps only)

Fahey and Puettmann, FEM 2008

CompetitorManagement – Partial disturbances

Conclusion

– Distinction between structure and composition

– Slow vegetation development- Short-term versus medium term

impacts of management practices- Choice of legacies

– Repeated disturbancesThinning and gap creation

– Attention to scale allows early seral legacies in mature forests

Acknowledgements: L. Kayes, P. Anderson, T. Harrington, M. Lopez, J. Shatford, D. Hibbs and all people

involved in the various thinning studies

Questions and comments?

[email protected]

Can We Emulate Early Seral Forest Through Silviculture

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